Capacitive sensor and detection method using the same

ABSTRACT

The present invention provides a capacitive sensor and detection method using the same. The capacitive sensor of the present invention includes at least one detecting plate and at least one reference plate surrounding each detecting plate. All of the reference plates are electrically coupled to the same first wire, and each reference plate is electrically coupled to a second wire. When an electrical signal is provided to the first wire and each second wire, one or more detecting plates touched or approached can be detected simultaneously based on the signal difference between each second wire and the first wire.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a capacitive sensor and detectionmethod using the same, and more particularly, to a capacitive sensorcapable of detecting multiple simultaneous touches and a detectionmethod using the same.

2. Description of the Prior Art

In portable electronic devices, many physical man-machine interfaces arerequired to allow users to input data or instructions. The most commoninterface is mechanical keys. However, mechanical keys are easilydamaged due to overuse, especially those that are commonly used. Inaddition, keys may be pressed when storing the portable electronicdevices, causing elastic fatigue or poor contact of the keys.

For smart phones or tablet PCs, capacitive sensors are often used askeys. Compared to physical keys, capacitive sensors are not prone todamage from overuse. However, since the screen generates a lot of noisesthat constantly change, it is easy for capacitive sensors to makemistakes due to noise interferences.

From the above it is clear that prior art still has shortcomings. Inorder to solve these problems, efforts have long been made in vain,while ordinary products and methods offering no appropriate structuresand methods. Thus, there is a need in the industry for a novel techniquethat solves these problems.

SUMMARY OF THE INVENTION

The present invention provides a capacitive sensor and detection methodusing the same. The capacitive sensor of the present invention includesat least one detecting plate and at least one reference platesurrounding each detecting plate. All of the reference plates areelectrically coupled to the same first wire, and each reference plate iselectrically coupled to a second wire. When an electrical signal isprovided to the first wire and each second wire, one or more detectingplates touched or approached can be detected simultaneously based on thesignal difference between each second wire and the first wire.

The capacitive sensor of the present invention can be covered by aninsulating protective layer, so detection can be carried out withoutdirection touching, avoiding problems such as elastic fatigue or poorcontact with mechanical keys after repetitive uses. In addition, thecapacitive sensor of the present invention performs detection bycomparing signals of the first wire and each second wire, so it has goodnoise resistance that is suitable for disposing in front of a display,and it is also capable of simultaneously detecting multiple touches.

An objective of the present invention is to overcome the shortcomings ofthe prior art by providing a novel capacitive sensor and detectionmethod using the same, wherein the signal of a reference plate iscompared with the signal of each detecting plate in order to determinethe detecting plate being touched or approached by an external object.It is of practical use.

The objectives of the present invention can be achieved by the followingtechnical schemes. The present invention provides a detection method ofa capacitive sensor, which includes: providing a first wire and aplurality of second wires; continuously providing an electrical signalto the first wire and each second wire; and each time the electricalsignal being provided, identifying a signal of each second wire being afirst type or a second type based on a signal difference between eachsecond wire and the first wire.

The objectives of the present invention can be further achieved by thefollowing technical schemes.

The first wire and each second wire are electrically coupled to at leastone conductor, respectively, wherein the total dimension of the at leastone conductor to which the first wire electrically coupled and the totaldimension of the at least one conductor to which each second wireelectrically coupled is equal or approximately equal.

When none of the conductors is touched or approached by an externalobject, the signals of the first wire and each second wire are equal orapproximately equal.

The at least one conductor to which the first wire electrically coupleddefines a plurality of spaces, and the at least one conductor to whicheach second wire electrically coupled resides in one of these spaces.

If the at least one conductor to which any second wire electricallycoupled is touched or approached by an external object, the signal ofthis second wire is one of the first and second types, and if the atleast one conductor to which any second wire electrically coupled is nottouched or approached by an external object, the signal of this secondwire is the other of the first and second types.

When the signal of at least one second wire is the first type and thesignal of at least one second wire is the second type, then the at leastone conductor electrically coupled to the first wire is touched orapproached by an external object.

If the signal difference between a second wire and the first wire ispositive, then the signal of the second wire is one of the first andsecond types, and if the signal difference between a second wire and thefirst wire is negative, then the signal of the second wire is the otherof the first and second types.

When the electrical signal is provided a first time and a second time,the signal difference between a second wire and the first wire is afirst signal difference and a second signal difference, respectively,and the signal of each second wire is identified as the first type orthe second type based on the first signal difference and the secondsignal difference.

The signal of each second wire is identified as the first type or thesecond type based on the difference between the first signal differenceand the second signal difference and a threshold.

Said detection method of a capacitive sensor further includes providingat least one shielding line, wherein the first wire and the second wiresare arranged in parallel with a controller, the at least one shieldingline is at both sides of the portions of the first wire and the secondwires that are arranged in parallel.

The area of a side of the at least one conductor electrically coupled toeach second wire facing towards a touch-sensitive sensor is smaller thanthat of opposite side, wherein the area of the side facing thetouch-sensitive sensor and the area of the opposite side can be areas ina range with the same width between the two sides.

The objectives of the present invention can also be achieved by thefollowing technical schemes. The present invention provides a capacitivesensor, which includes: a first wire; at least one second wire; at leastone detector including: at least one reference plate for defining atleast one space, and all of the reference plates being electricallycoupled to the first wire; at least one detecting plate, each of whichresiding in one of the at least one space and being electrically coupledto one of the at least one second wire; and a controller for providingan electrical signal to the first wire and each second wire, anddetecting a touch or approach by an external object with respect to eachdetecting plate based on a corresponding signal difference between eachsecond wire and the first wire, respectively.

The objectives of the present invention can be further achieved by thefollowing technical schemes.

The dimension of each detecting plate is equal or approximately equalthe total dimension of all of the reference plates.

The at least one reference plate defines a space in which the detectingplate resides, and the at least one reference plate defines an openingthrough which a corresponding second wire is electrically coupled to thedetecting plate.

The space is defined by a single reference plate.

Each detector includes at least two reference plates, and the at leasttwo reference plates and a portion of the first wire surround thedetecting plate and define an opening through which a correspondingsecond wire is electrically coupled to the detecting plate.

The corresponding signal difference of each detector touched orapproached by the external object is greater or less than a threshold,wherein the corresponding signal difference of each detector is thesignal difference between a corresponding second wire and the firstwire.

When the corresponding signal difference of each detector touched orapproached by the external object is positive, the corresponding signaldifference of each detector not touched or approached by the externalobject is negative, wherein the corresponding signal difference of eachdetector is the signal difference between a corresponding second wireand the first wire.

When the corresponding signal difference of each detector touched orapproached by the external object is negative, the corresponding signaldifference of each detector not touched or approached by the externalobject is positive, wherein the corresponding signal difference of eachdetector is the signal difference between a corresponding second wireand the first wire.

A corresponding signal difference of each detector before and after atouch or approach is a first signal difference and a second signaldifference, respectively, and the difference between and first andsecond signal differences is greater or less than a threshold.

Said capacitive sensor further includes a shielding line, whichsurrounds the at least one detector, the first wire and each secondwire.

The area of a side of each detecting plate facing towards atouch-sensitive sensor is smaller than that of opposite side, whereinthe area of the side facing the touch-sensitive sensor and the area ofthe opposite side can be areas in a range with the same width betweenthe two sides.

The objectives of the present invention can also be achieved by thefollowing technical schemes. The present invention provides a capacitivesensor using signal differences for detection, which includes: a firstwire; at least one second wire; at least one reference plate fordefining at least one space, and all of the reference plates beingelectrically coupled to the first wire; at least one detecting plate,each of which residing in one of the at least one space and beingelectrically coupled to one of the at least one second wire; and acontroller for performing at least the following operations: providingan electrical signal to the first wire and each second wire continuouslyat a plurality of periods to obtain a reference value of the first wireand a detection value of each second wire; taking one of the periods asan initial period, while other periods as detecting periods; in theinitial period, recording the difference between each detection valueand the reference value an initial difference; in each detecting period,generating each detection value and the reference value as a detectiondifference for each detection value; and in each detecting period,identifying a detection value as one of first and second types if itsdetection difference is greater or less than the initial difference by athreshold, and a detection value is identified as the other of the firstor second types if its detection difference is not greater or less thanthe initial difference by the threshold.

The objectives of the present invention can further be achieved by thefollowing technical schemes.

When the detection difference of each detection value identified as thefirst type is greater than the initial difference, the detectiondifference of each detection value identified as the second type is lessthan the initial difference.

When the detection difference of each detection value identified as thefirst type is less than the initial difference, the detection differenceof each detection value identified as the second type is greater thanthe initial difference.

The reference value is generated based on the signal of at least onereference plate, the at least one reference plate defines a plurality ofspaces, and each detection value is generated based on the signal of oneof the plurality of detecting plates, each detecting plate resides inone of these spaces.

The dimension of each detecting plate is equal or approximately equalthe total dimension of all of the reference plates.

The area of a side of each detecting plate facing towards atouch-sensitive sensor is smaller than that of opposite side, whereinthe area of the side facing the touch-sensitive sensor and the area ofthe opposite side can be areas in a range with the same width betweenthe two sides.

The objectives of the present invention can also be achieved by thefollowing technical schemes. The present invention provides a detectionmethod of a capacitive sensor using signal differences, which includes:providing a reference value and a plurality of detection valuescontinuously at a plurality of periods; taking one of the periods as aninitial period, while other periods as detecting periods; in the initialperiod, recording the difference between each detection value and thereference value an initial difference; in each detecting period,generating each detection value and the reference value as a detectiondifference for each detection value; and in each detecting period,identifying a detection value as one of first and second types if itsdetection difference is greater or less than the initial difference by athreshold, and a detection value is identified as the other of the firstor second types if its detection difference is not greater or less thanthe initial difference by the threshold.

The objectives of the present invention can further be achieved by thefollowing technical schemes.

When the detection difference of each detection value identified as thefirst type is greater than the initial difference, the detectiondifference of each detection value identified as the second type is lessthan the initial difference.

When the detection difference of each detection value identified as thefirst type is less than the initial difference, the detection differenceof each detection value identified as the second type is greater thanthe initial difference.

The reference value is generated based on the signal of at least onereference plate, the at least one reference plate defines a plurality ofspaces, and each detection value is generated based on the signal of oneof a plurality of detecting plates, each detecting plate resides in oneof these spaces.

The dimension of each detecting plate is equal or approximately equalthe total dimension of all of the reference plates.

The area of a side of each detecting plate facing towards atouch-sensitive sensor is smaller than that of opposite side, whereinthe area of the side facing the touch-sensitive sensor and the area ofthe opposite side can be areas in a range with the same width betweenthe two sides.

Compared to the prior art, the present invention has significantadvantages and beneficial effects. With the above technical schemes, thecapacitive sensor and the detection method using the same exhibit atleast the following advantages and beneficial effects:

-   -   capable of detecting one touch or approach by an external object        or simultaneously detecting multiple touches or approaches by an        external object;    -   capable of detecting the change of state of one signal or        simultaneously detecting the changes of states of multiple        signals; and    -   having high noise resistance suitable for disposing in front of        displays that emit noises in different levels.

The above description is only an outline of the technical schemes of thepresent invention. Preferred embodiments of the present invention areprovided below in conjunction with the attached drawings to enable onewith ordinary skill in the art to better understand said and otherobjectives, features and advantages of the present invention and to makethe present invention accordingly.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more fully understood by reading thefollowing detailed description of the preferred embodiments, withreference made to the accompanying drawings, wherein:

FIGS. 1 to 4 are schematic diagrams depicting a capacitive sensoraccording to a first embodiment of the present invention;

FIG. 5 is a flowchart illustrating a detection method of a capacitivesensor according to a second embodiment of the present invention;

FIG. 6 is a flowchart illustrating a detection method of a capacitivesensor using signal differences according to a third embodiment of thepresent invention; and

FIG. 7 is a schematic diagram depicting a capacitive sensor according toa fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Some embodiments of the present invention are described in detailsbelow. However, in addition to the descriptions given below, the presentinvention can be applicable to other embodiments, and the scope of thepresent invention is not limited by such, rather by the scope of theclaims. Moreover, for better understanding and clarity of thedescription, some components in the drawings may not necessary be drawnto scale, in which some may be exaggerated relative to others, andirrelevant parts are omitted.

According to a first embodiment of the present invention, a capacitivesensor is provided, which includes a first wire, at least one secondwire, at least one reference plate, at least one detecting plate, acontroller, and a shielding line. The at least one detecting platedefines (or separates out) at least one space, and all reference platesare electrically coupled to the first wire. In addition, each detectingplate is electrically coupled to a second wire. Moreover, the controllerprovides electrical signals to the first wire and each second wire, anddetects touching or approaching by an external object based on thesignal difference between each second wire and the first wire,respectively.

For example, as shown in FIG. 1, a capacitive sensor 1 includes a firstwire 13, at least one second wire 14, at least one detector 10 and acontroller 16, wherein each detector 10 includes a detecting plate 11and a reference plate 12. The reference plate 12 is in the shape of “U”,which defines a space in which the detecting plate 11 resides, and thedetecting plate 11 is electrically coupled to a second wire 14. Althoughthree detectors 10 are shown in FIG. 1, one with ordinary skill in theart can appreciate that the number of detectors may include, but is notlimited to, three.

In an example of the present invention, the capacitive sensor includesat least one detector. Each detector includes a detecting plate and atleast one reference plate. The at least one reference plate defines aspace in which the detecting plate resides.

As another example, referring to FIG. 2, a capacitive sensor 2 includesa first wire 13, at least one second wire 14, at least one detector 20and a controller 16, wherein each detector 20 includes a detecting plate21 and two reference plates 22. The two reference plates 22 defines aspace in which the detecting plate 21 resides, and the detecting plate21 is electrically coupled to a second wire 14. The space may also beregarded as defined by the two reference plates 22 and the first wire13. Although three detectors 20 are shown in FIG. 2, one with ordinaryskill in the art can appreciate that the number of detectors 20 mayinclude, but is not limited to, three.

In another example of the present invention, the capacitive sensorincludes at least one reference plate for defining a plurality ofspaces, and all reference plates are coupled to the first wire. Eachdetecting plate resides in a space, respectively, and is electricallycoupled to a second wire, respectively.

As shown in FIG. 3, a capacitive sensor 3 includes a reference plate 32(e.g. formed by four pieces of reference plates connected together orformed integrally by a single reference plate) or four reference plates32 for defining four spaces, and a detecting plate 31 is disposed ineach of the spaces.

Alternatively, as shown in FIG. 4, a capacitive sensor 4 includes areference plate 42 (e.g. formed by a plurality of reference platesconnected together or formed integrally by a single reference plate) ora plurality of reference plates 42 for defining a plurality of spaces,and a detecting plate 41 is disposed in each of the spaces.

Moreover, in FIGS. 1 to 4, the shielding line 15 generally surrounds thefirst wire 13, the at least one second wire 14, the at least onereference plate (12, 22, 32, and 42), and the at least one detectingplate (11, 21, 31, and 41), and is electrically coupled to thecontroller 16. In an example of the present invention, the first wire 13and all second wires 14 can be arranged in parallel with respect to thecontroller 16. The shielding line 15 may consist of one or multiplelines disposed at either side of the first wire 13 and all second wires14. In another example of the present invention, there are two shieldinglines 15, each disposed at one of two sides of the first wire 13 and allsecond wires 14 arranged in parallel.

In an example of the present invention, the first wire 13 and the atleast one second wire 14 are connected to the controller in a parallelfashion. For example, a portion of the first wire 13 and the at leastone second wire 14 are arranged in parallel on a flat printed circuitboard or flexible cable. In addition, the shielding line 15 may includeone or two lines disposed at either side of the first wire 13 and the atleast one second wire 14. In an example of the present invention, theshielding line 15, the first wire 13, and the at least one second wire14 are simultaneously provided with the same electrical signal.Accordingly, when there is no touching or approaching by an externalobject, both sides of the first wire 13 and each of the at least onesecond wire 14 will have symmetrical electrical fields. Therefore, whenthere is no touching or approaching by an external object, both sides ofthe portion of the first wire 13 and each of the at least one secondwire 14 arranged in parallel with the controller 16 will havesymmetrical electrical fields.

One with ordinary skill in the art can appreciate that the shape of thedetecting plate in this present invention includes, but is not limitedto, square, rectangle, fan, triangle, circle, oval, polygon, or othergeometric pattern.

In an example of the present invention, the electrical signal providedby the controller to the first wire and the second wire can be a pulsewidth modulated (PWM) signal or other types of AC signal; the presentinvention is not limited to these. The electrical signal can becontinuously provided. In an example of the present invention, theelectrical signal can be continuously provided at intervals; in anotherexample of the present invention, the electrical signal can becontinuously provided persistently.

In addition, the controller may detect the capacitive coupling of aconductor connected with the first wire and the second wire by anintegrator to detect the magnitude of the signal or signal variation.Moreover, the signal difference between each of the second wire and thefirst wire can be generated by one or more differential amplifiers. Onewith ordinary skill in the art can appreciate that the signal differencecan also be generated by other forms of subtractors; the presentinvention is not limited to these.

FIG. 5 is a detection method of a capacitive sensor according to asecond embodiment of the present invention. First, as shown in step 510,a first wire 13 and a plurality of second wires 14 are provided. Then,in step 520, an electrical signal is continuously provided to the firstwire 13 and each of the second wires 14. In addition, in step 530, eachtime the electrical signal is provided, the signal of each second wire14 is determined to be of a first or second type based on the signaldifference between each of the second wires 14 and the first wire 13.

In an example of the present invention, steps 520 and 530 can be carriedout by the controller 16. The first wire 13 and each of the second wires14 provided in step 510 are electrically coupled to at least oneconductor, respectively. The total dimension of at least one conductorto which the first wire 13 electrically coupled is equal orapproximately equal to the total dimension of at least one conductor towhich each second wire 14 electrically coupled. For example, in FIGS. 1to 4, the first wire 13 is electrically coupled to a plurality ofreference plates 12, 22, 32, or 42, and each second wire 14 iselectrically coupled to a detecting plate 11, 21, 31, or 41. One withordinary skill in the art can appreciate that the detecting plate 11 mayconstitute a plurality of sub-detecting plates, that is, each secondwire 14 can also be electrically coupled to the plurality ofsub-detecting plates. In an example of the present invention, the atleast one conductor to which the first wire 13 electrically coupleddefines a plurality of spaces, and the at least one conductor to whicheach second wire 14 electrically coupled resides in one of the spaces,respectively.

Since the total dimension of at least one conductor to which the firstwire 13 electrically coupled is equal or approximately equal to thetotal dimension of at least one conductor to which each second wire 14electrically coupled, when there is no external object touching orapproaching all conductors, the signals of the first wire 13 and eachsecond wire 14 are equal or approximately equal. In an example of thepresent invention, all the conductors can be covered with an insulatinglayer. This insulating layer can be transparent or opaque, such as atransparent glass or film. A touch or approach by an external object maymean that the external object touches or approaches the insulatinglayer.

The external object may be physically or virtually grounded, forexample, may be a body part (e.g. a finger) of a human standing on theground. When the external object touches or approaches a conductor, thesignal of the conductor varies with the distance and area of the touchby the external object. Therefore, when an external objectsimultaneously approaches or touches a detecting plate and a portion ofa reference plate, the area on the detecting plate that corresponds tothe touch or approach of the external object is relatively bigger thanthe area on the reference plate that corresponds to the touch orapproach of the external object. In other words, the signal variation ofa second wire 14 electrically coupled to a detecting plate being touchedor approached by the external object will be greater than the signalvariation of the first wire 13 (electrically coupled to all referenceplates). Conversely, the signal variation of a second wire 14electrically coupled to a detecting plate not touched or approached bythe external object will be less than the signal variation of the firstwire 13. As a result, it can be determined that whether a detectingplate is being touched or approached by an external object (e.g. as oneof first and second types) or not (as the other of first and secondtypes) based on the signals of the second wire 14 and the first wire 13.

For example, the touch or approach of the external object will cause thesignal to reduce. Thus, it can be determined that whether a detectingplate electrically coupled to each second wire 14 is being touched orapproached directly based on the signal difference of each second wire14 and the first wire 13. For example, when the signal difference isgreater or less than a threshold, there is a touch or approach by anexternal object. The signal difference when no external touch orapproach exists can also be used as a reference. For example, the signaldifference detected during an initial period may be used as the signaldifference when no external touch or approach exists, which issubsequently compared with signal differences detecting during aplurality of consecutive detecting periods. When the difference betweenthe signal differences of the initial period and a detecting period isgreater or less than a threshold, there is a touch or approach by anexternal object. In an example of the present invention, when the signaldifference exceeds a predetermined range or the difference between thesignal differences of the initial period and a detecting period exceedsa predetermined range, there is a touch or approach by an externalobject, and vice versa. This predetermined range can be less or greaterthan a threshold.

In an example of the present invention, a sign (positive or negative) ofthe signal difference or the difference between the signal differencesof an initial period and a detecting period can be used to determinewhether it is a first type or a second type. For example, if the signaldifference between a second wire 14 and the first wire 13 is positive,then the signal of the second wire 14 is one of the first and secondtypes, and if the signal difference between a second wire 14 and thefirst wire 13 is negative, then the signal of the second wire 14 is theother of the first or second types.

Thus, when some of the detecting plates are touched or approached andsome of the detecting plates are not touched or approached, a conductorelectrically coupled to at least one second wire 14 will be identifiedas the first type, and a conductor electrically coupled to at least onesecond wire 14 will be identified as the second type, wherein theconductor electrically coupled to the first wire 13 is touched orapproached by the external object.

By comparing signals of each second wire 14 and the first wire 13 of thecapacitive sensor of the present invention, one or more detecting platestouched or approached by an external object can be determined. Thecomparison of the signals of the two can be performed by a comparator,or a signal difference between the two can be generated by adifferential amplifier for comparison, or the signals of the two can beconverted into digital difference for comparison, or the signals of thetwo can be converted into digital value before comparison is made. Thepresent invention is not limited to the signal comparison methods justdescribed, and one with ordinary skill in the art can appreciate othertypes of signal comparison methods which will not be described anyfurther.

The capacitive sensor of the present invention can be used as keys, asshown in FIGS. 1 and 2, for example, each detecting plate can correspondto an independent key. The capacitive sensor of the present invention isable to detect a plurality of simultaneous key presses. Keys can also bedesigned as arrow keys, as shown in FIG. 3, which include up, right,down, and left arrow keys. One with ordinary skill in the art canappreciate other types of arrow keys, such as those including 8directions, or multiple directions, such as that shown in FIG. 4, whichis a circular multi-directional sensor that can be used as a jog dialand etc.

In an example of the present invention, a plurality of capacitivesensors can be combined together. For example, there can be multiplesets of capacitive sensors. Each capacitive sensor includes a firstwire, at least one second wire, at least one reference plate, at leastone detecting plate, a controller, and a shielding line. The at leastone detecting plate defines (or separates out) at least one space, andall reference plates are electrically coupled to the first wire. Inaddition, each detecting plate is electrically coupled to a second wire.Moreover, the controller provides electrical signals to the first wireand each second wire, and detects a touching or approaching of eachdetector by an external object based on the signal difference betweeneach second wire and the first wire, respectively. As a result, alldetecting plates can form a detecting plate matrix.

These capacitive sensors can each have an independent first wire 13 anda plurality of second wires 14, directly connected to the controller 16,or jointly connected to a wire of the controller 16 through the controlof a switch. At any one time, there is only one capacitive sensor (i.e.the first wire 13 and the plurality of second wires 14) electricallycoupled to the controller 16.

FIG. 6 is a detection method of a capacitive sensor using signaldifferences according to a third embodiment of the present invention.First, in step 610, a reference value and a plurality of detectionvalues are provided continuously at a plurality of periods, and then, instep 620, one of the periods is taken as an initial period, while otherperiods are taken as detecting periods. For example, the first period istaken as the initial period, or an arbitrary period is taken as theinitial period. Steps 610 and 620 can be performed repetitively.

Next, in step 630, in the initial period, the difference between eachdetection value and the reference value is recorded as an initialdifference. Then, in step 640, in each detecting period, each detectionvalue and the reference value are generated as a detection differencefor each detection value. In addition, in step 650, in each detectingperiod, a detection value is identified as one of first and second typesif its detection difference is greater or less than the initialdifference by a threshold, and a detection value is identified as theother of the first or second types if its detection difference is notgreater or less than the initial difference by the threshold. Steps 630,640, and 650 can be performed repetitively following steps 610 and 620.Moreover, steps 610 to 650 can be performed by the controller 160.

The above method can be applied to a capacitive sensor using signaldifferences for detection, the sensor can include: a first wire; atleast one second wire; at least one reference plate for defining atleast one space, and all of the reference plates being electricallycoupled to the first wire; at least one detecting plate, each of whichresiding in one of the at least one space and being electrically coupledto one of the at least one second wire; and a controller for performingat least the following operations: providing an electrical signal to thefirst wire and each second wire continuously at a plurality of timeperiods to obtain a reference value and a plurality of detection values,respectively; taking one of the periods as an initial period, whileother periods as detecting periods; in the initial period, recording thedifference between each detection value and the reference value aninitial difference; in each detecting period, generating each detectionvalue and the reference value as a detection difference for eachdetection value; in each detecting period, identifying a detection valueas one of first and second types if its detection difference is greateror less than the initial difference by a threshold, and a detectionvalue is identified as the other of the first or second types if itsdetection difference is not greater or less than the initial differenceby the threshold.

In an example of the present invention, the reference value is generatedbased on the signal of at least one reference plate. The at least onereference plate defines a plurality of spaces, and each detection valueis generated based on the signal of one of a plurality of detectingplates. Each detecting plate resides in one of these spaces.

In another example of the present invention, when the detectiondifference of a detection value identified as the first type is greaterthan the initial difference, the detection difference of a detectionvalue identified as the second type is less than the initial difference.Conversely, when the detection difference of a detection valueidentified as the first type is less than the initial difference, thedetection difference of a detection value identified as the second typeis greater than the initial difference. For example, in some detectingperiods, the reference value and at least one detection value change(increase or decrease) simultaneously, wherein the at least onedetection value varies considerably more than the reference value, sothe detection difference of said at least one detection value becomeslarger or smaller. On the contrary, the detection differences of otherdetection values will change in the opposite manner.

One with ordinary skill in the art can recognize that the referencevalue and each detection value in the initial period may or may not beapproximately equal. Similarly, one with ordinary skill in the art canrecognize that the dimensions of the conductors electrically coupled tothe first wire and each second wire may or may not be approximatelyequal. The present invention includes, but is not limited to, thedimensions of the conductors electrically coupled to the first wire andeach second wire being equal or approximately equal.

In addition, the first and second types can be sued to represent twostates, one representing a change of state, while the other representingno change of state. For example, the first type may represent a signalchanged due to an external object touching or approaching a conductor,and the second type may represent a signal unchanged due to no externalobject touching or approaching a conductor. As another example, thefirst and second types can be applied to the use of switches. When thereference value exceeds a threshold, and at least one detection valuevaries considerably more than the reference value, the detectiondifference of an unchanged detection value will be greater than athreshold. This can be used to determine the unchanged detection valueas one of open and close states, while other detection values as theother state.

Referring to FIG. 7, a capacitive sensor 7 is provided according to afourth embodiment of the present invention. The capacitive sensor 7includes a plurality of reference plates 72 and a plurality of detectingplates 71. In addition, this embodiment further includes atouch-sensitive sensor 17 adjacent to the capacitive sensor 7. Althoughfive detectors 70 are shown in FIG. 7 as an example, one with ordinaryskill in the art can appreciate that the number of the detectorsincludes, but is not limited to, five. When an external object touchesor approaches the touch-sensitive sensor 17, it provides sensinginformation indicating the location of the external object in order tointerpret the location of the external object. For example, the sensinginformation can be received by a controller 16, which determines thelocation of the external object. One with ordinary skill in the art canrecognize that the touch-sensitive sensor 17 can be capacitive,resistive, surface acoustic, infrared, optical, and so on. The detectionmethod of the sensing information is prior art, and will not bedescribed any further.

In an example of the present invention, the area of a side of thedetecting plate 71 facing towards the touch-sensitive sensor 17 issmaller than that of opposite side, wherein the area of the side facingthe touch-sensitive sensor 17 and the area of the opposite side can beareas in a range with the same width between the two sides. For example,the detecting plate 71 is a triangle, with the summit pointing towardsthe touch-sensitive sensor 17, as shown in FIG. 7. Alternatively, oneside facing the touch-sensitive sensor 17 is in an arc shape, such as asemicircle or a semi-ellipse.

The area of the side of the detecting plate 71 facing towards thetouch-sensitive sensor 17 is determined based on the distance betweenthe detecting plate 71 and the touch-sensitive sensor 17.

For example, as shown by a touching area 77 in FIG. 7, when an externalobject simultaneously touches or approaches the touch-sensitive sensor17 and the detecting plate 71, the area of the detecting plate 71touched or approached by the external object is considerably small, sothe signal difference or the difference of the signal differencesbetween the initial and the detecting periods will not exceed thepredetermined range, thus it will not be regarded as an effective touch.On the contrary, as shown by a touching area 78 in FIG. 7, when thetouch or approach by the external object falls mainly on the detectingplate 71, the signal difference or the difference of the signaldifferences between the initial and the detecting periods will be enoughto exceed the predetermined range. Therefore, this can reducemisjudgment from occurring when the capacitive sensor 7 andtouch-sensitive sensor 17 are close to each other.

In previous description, the dimensions of two entities beingapproximately equal means that the dimensions of the two are exactlyequal or roughly equal, for example, the difference of the two is within10%, e.g. one is bigger than the other by no more than 10%. The totaldimension of at least one conductor to which the first wire 13electrically coupled and the total dimension of at least one conductorto which each second wire 14 electrically coupled differs by no morethan 10%.

The above embodiments are only used to illustrate the principles of thepresent invention, and they should not be construed as to limit thepresent invention in any way. The above embodiments can be modified bythose with ordinary skill in the art without departing from the scope ofthe present invention as defined in the following appended claims.

1. A detection method of a capacitive sensor, comprising: providing afirst wire and a plurality of second wires; continuously providing anelectrical signal to the first wire and each second wire; and each timethe electrical signal being provided, identifying a signal of eachsecond wire being a first type or a second type based on a signaldifference between each second wire and the first wire.
 2. The detectionmethod of a capacitive sensor of claim 1, wherein the first wire andeach second wire are electrically coupled to at least one conductor,respectively, wherein the total dimension of the at least one conductorto which the first wire electrically coupled and the total dimension ofthe at least one conductor to which each second wire electricallycoupled is equal or approximately equal.
 3. The detection method of acapacitive sensor of claim 2, wherein when none of the conductors istouched or approached by an external object, the signals of the firstwire and each second wire are equal or approximately equal.
 4. Thedetection method of a capacitive sensor of claim 2, wherein the at leastone conductor to which the first wire electrically coupled defines aplurality of spaces, and the at least one conductor to which each secondwire electrically coupled resides in one of these spaces.
 5. Thedetection method of a capacitive sensor of claim 2, wherein if the atleast one conductor to which any second wire electrically coupled istouched or approached by an external object, the signal of this secondwire is one of the first and second types, and if the at least oneconductor to which any second wire electrically coupled is not touchedor approached by an external object, the signal of this second wire isthe other of the first and second types.
 6. The detection method of acapacitive sensor of claim 2, wherein when the signal of at least onesecond wire is the first type and the signal of at least one second wireis the second type, then the at least one conductor electrically coupledto the first wire is touched or approached by an external object.
 7. Thedetection method of a capacitive sensor of claim 1, wherein if thesignal difference between a second wire and the first wire is positive,then the signal of the second wire is one of the first and second types,and if the signal difference between a second wire and the first wire isnegative, then the signal of the second wire is the other of the firstand second types.
 8. The detection method of a capacitive sensor ofclaim 1, wherein when the electrical signal is provided a first time anda second time, the signal difference between a second wire and the firstwire is a first signal difference and a second signal difference,respectively, and the signal of each second wire is identified as thefirst type or the second type based on the first signal difference andthe second signal difference.
 9. The detection method of a capacitivesensor of claim 8, wherein the signal of each second wire is identifiedas the first type or the second type based on the difference between thefirst signal difference and the second signal difference and athreshold.
 10. The detection method of a capacitive sensor of claim 1,further comprising providing at least one shielding line, wherein thefirst wire and the second wires are arranged in parallel with acontroller, the at least one shielding line is at both sides of theportions of the first wire and the second wires that are arranged inparallel.
 11. The detection method of a capacitive sensor of claim 2,wherein the area of a side of the at least one conductor electricallycoupled to each second wire facing towards a touch-sensitive sensor issmaller than that of opposite side, wherein the area of the side facingthe touch-sensitive sensor and the area of the opposite side can beareas in a range with the same width between the two sides.
 12. Acapacitive sensor, comprising: a first wire; at least one second wire;at least one detector, including: at least one reference plate fordefining at least one space, and all of the reference plates beingelectrically coupled to the first wire; at least one detecting plate,each of which residing in one of the at least one space and beingelectrically coupled to one of the at least one second wire; and acontroller for providing an electrical signal to the first wire and eachsecond wire, and detecting a touch or approach by an external objectwith respect to each detecting plate based on a corresponding signaldifference between each second wire and the first wire, respectively.13. The capacitive sensor of claim 12, wherein the dimension of eachdetecting plate is equal or approximately equal the total dimension ofall of the reference plates.
 14. The capacitive sensor of claim 12,wherein the at least one reference plate defines a space in which thedetecting plate resides, and the at least one reference plate defines anopening through which a corresponding second wire is electricallycoupled to the detecting plate.
 15. The capacitive sensor of claim 14,wherein the space is defined by a single reference plate.
 16. Thecapacitive sensor of claim 12, wherein each detector includes at leasttwo reference plates, and the at least two reference plates and aportion of the first wire surround the detecting plate and define anopening through which a corresponding second wire is electricallycoupled to the detecting plate.
 17. The capacitive sensor of claim 12,wherein the corresponding signal difference of each detector touched orapproached by the external object is greater or less than a threshold,wherein the corresponding signal difference of each detector is thesignal difference between a corresponding second wire and the firstwire.
 18. The capacitive sensor of claim 12, wherein when thecorresponding signal difference of each detector touched or approachedby the external object is positive, the corresponding signal differenceof each detector not touched or approached by the external object isnegative, wherein the corresponding signal difference of each detectoris the signal difference between a corresponding second wire and thefirst wire.
 19. The capacitive sensor of claim 12, wherein when thecorresponding signal difference of each detector touched or approachedby the external object is negative, the corresponding signal differenceof each detector not touched or approached by the external object ispositive, wherein the corresponding signal difference of each detectoris the signal difference between a corresponding second wire and thefirst wire.
 20. The capacitive sensor of claim 12, wherein acorresponding signal difference of each detector before and after atouch or approach is a first signal difference and a second signaldifference, respectively, and the difference between and first andsecond signal differences is greater or less than a threshold.
 21. Thecapacitive sensor of claim 12, further comprising a shielding line,which surrounds the at least one detector, the first wire and eachsecond wire.
 22. The method of claim 12, wherein the area of a side ofeach detecting plate facing towards a touch-sensitive sensor is smallerthan that of opposite side, wherein the area of the side facing thetouch-sensitive sensor and the area of the opposite side can be areas ina range with the same width between the two sides.
 23. A capacitivesensor using signal differences for detection, comprising: a first wire;at least one second wire; at least one reference plate for defining atleast one space, and all of the reference plates being electricallycoupled to the first wire; at least one detecting plate, each of whichresiding in one of the at least one space and being electrically coupledto one of the at least one second wire; and a controller for performingat least the following operations: providing an electrical signal to thefirst wire and each second wire continuously at a plurality of periodsto obtain a reference value of the first wire and a detection value ofeach second wire; taking one of the periods as an initial period, whileother periods as detecting periods; in the initial period, recording thedifference between each detection value and the reference value aninitial difference; in each detecting period, generating each detectionvalue and the reference value as a detection difference for eachdetection value; and in each detecting period, identifying a detectionvalue as one of first and second types if its detection difference isgreater or less than the initial difference by a threshold, and adetection value is identified as the other of the first or second typesif its detection difference is not greater or less than the initialdifference by the threshold.
 24. The capacitive sensor using signaldifferences for detection of claim 23, wherein when the detectiondifference of each detection value identified as the first type isgreater than the initial difference, the detection difference of eachdetection value identified as the second type is less than the initialdifference.
 25. The capacitive sensor using signal differences fordetection of claim 23, wherein when the detection difference of eachdetection value identified as the first type is less than the initialdifference, the detection difference of each detection value identifiedas the second type is greater than the initial difference.
 26. Thecapacitive sensor using signal differences for detection of claim 23,wherein the reference value is generated based on the signal of at leastone reference plate, the at least one reference plate defines aplurality of spaces, and each detection value is generated based on thesignal of one of the plurality of detecting plates, each detecting plateresides in one of these spaces.
 27. The capacitive sensor using signaldifferences for detection of claim 23, wherein the dimension of eachdetecting plate is equal or approximately equal the total dimension ofall of the reference plates.
 28. The capacitive sensor using signaldifferences for detection of claim 23, wherein the area of a side ofeach detecting plate facing towards a touch-sensitive sensor is smallerthan that of opposite side, wherein the area of the side facing thetouch-sensitive sensor and the area of the opposite side can be areas ina range with the same width between the two sides.
 29. A detectionmethod of a capacitive sensor using signal differences, comprising:providing a reference value and a plurality of detection valuescontinuously at a plurality of periods; taking one of the periods as aninitial period, while other periods as detecting periods; in the initialperiod, recording the difference between each detection value and thereference value an initial difference; in each detecting period,generating each detection value and the reference value as a detectiondifference for each detection value; and in each detecting period,identifying a detection value as one of first and second types if itsdetection difference is greater or less than the initial difference by athreshold, and a detection value is identified as the other of the firstor second types if its detection difference is not greater or less thanthe initial difference by the threshold.
 30. The detection method of acapacitive sensor using signal differences of claim 29, wherein when thedetection difference of each detection value identified as the firsttype is greater than the initial difference, the detection difference ofeach detection value identified as the second type is less than theinitial difference.
 31. The detection method of a capacitive sensorusing signal differences of claim 29, wherein when the detectiondifference of each detection value identified as the first type is lessthan the initial difference, the detection difference of each detectionvalue identified as the second type is greater than the initialdifference.
 32. The detection method of a capacitive sensor using signaldifferences of claim 29, wherein the reference value is generated basedon the signal of at least one reference plate, the at least onereference plate defines a plurality of spaces, and each detection valueis generated based on the signal of one of a plurality of detectingplates, each detecting plate resides in one of these spaces.
 33. Thedetection method of a capacitive sensor using signal differences ofclaim 32, wherein the dimension of each detecting plate is equal orapproximately equal the total dimension of all of the reference plates.34. The detection method of a capacitive sensor using signal differencesof claim 32, wherein the area of a side of each detecting plate facingtowards a touch-sensitive sensor is smaller than that of opposite side,wherein the area of the side facing the touch-sensitive sensor and thearea of the opposite side can be areas in a range with the same widthbetween the two sides.